Submission #1039368

#	Time	Username	Problem	Language	Result	Execution time	Memory
1039368		Ludissey	Mecho (IOI09_mecho)	C++17	84 / 100	399 ms	12900 KiB

mecho

#include <bits/stdc++.h>
#define int long long
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
 
using namespace std;
vector<vector<bool>> visited;
vector<vector<int>> dist;
 
vector<vector<char>> grid;
vector<vector<int>> beeT;
pair<int,int> home;
pair<int,int> bear;
int N,S;
bool f(int t){
    priority_queue<pair<int,pair<int,int>>> q;
    visited.clear();
    dist.clear();
    visited.resize(N,vector<bool>(N,false));
    dist.resize(N,vector<int>(N,1e14));
    dist[bear.first][bear.second]=t*S;
    q.push({-t*S,bear});
    while(!q.empty()){
        int x=q.top().second.first,y=q.top().second.second; q.pop();
        if((dist[x][y])/S>=beeT[x][y]&&grid[x][y]!='D') continue;
        if(visited[x][y]) continue;
        visited[x][y]=true;
        if(x-1>=0&&(grid[x-1][y]=='G'||grid[x-1][y]=='M'||grid[x-1][y]=='D')&&dist[x][y]+1<dist[x-1][y]){
            dist[x-1][y]=dist[x][y]+1;
            q.push({-dist[x-1][y], {x-1,y}});
        }
        if(x+1<N&&(grid[x+1][y]=='G'||grid[x+1][y]=='M'||grid[x+1][y]=='D')&&dist[x][y]+1<dist[x+1][y]){
            dist[x+1][y]=dist[x][y]+1;
            q.push({-dist[x+1][y], {x+1,y}});
        }
        if(y-1>=0&&(grid[x][y-1]=='G'||grid[x][y-1]=='M'||grid[x][y-1]=='D')&&dist[x][y]+1<dist[x][y-1]){
            dist[x][y-1]=dist[x][y]+1;
            q.push({-dist[x][y-1], {x,y-1}});
        }
        if(y+1<N&&(grid[x][y+1]=='G'||grid[x][y+1]=='M'||grid[x][y+1]=='D')&&dist[x][y]+1<dist[x][y+1]){
            dist[x][y+1]=dist[x][y]+1;
            q.push({-dist[x][y+1], {x,y+1}});
        }
    }
    return visited[home.first][home.second];
}
 
signed main() {
    ios_base::sync_with_stdio(false); cin.tie(nullptr);
    cin >> N >> S;
    grid.resize(N,vector<char>(N));
    visited.resize(N,vector<bool>(N,false));
    for (int i = 0; i < N; i++) { for (int j = 0; j < N; j++) cin >> grid[i][j]; }
    for (int i = 0; i < N; i++) { for (int j = 0; j < N; j++){
        if(grid[i][j]=='M') bear={i,j};
        else if(grid[i][j]=='D') home={i,j};
    } 
    }
    beeT.resize(N,vector<int>(N,1e14));
    priority_queue<pair<int,pair<int,int>>> q;
    for (int i = 0; i < N; i++) { for (int j = 0; j < N; j++) if(grid[i][j]=='H') { q.push({0,{i,j}}); beeT[i][j]=0; }}
    while(!q.empty()){
        int x=q.top().second.first,y=q.top().second.second; q.pop();
        if(visited[x][y]) continue;
        visited[x][y]=true;
        if(x-1>=0&&(grid[x-1][y]=='G'||grid[x-1][y]=='M')&&beeT[x][y]+1<beeT[x-1][y]){
            beeT[x-1][y]=beeT[x][y]+1;
            q.push({-beeT[x-1][y], {x-1,y}});
        }
        if(x+1<N&&(grid[x+1][y]=='G'||grid[x+1][y]=='M')&&beeT[x][y]+1<beeT[x+1][y]){
            beeT[x+1][y]=beeT[x][y]+1;
            q.push({-beeT[x+1][y], {x+1,y}});
        }
        if(y-1>=0&&(grid[x][y-1]=='G'||grid[x][y-1]=='M')&&beeT[x][y]+1<beeT[x][y-1]){
            beeT[x][y-1]=beeT[x][y]+1;
            q.push({-beeT[x][y-1], {x,y-1}});
        }
        if(y+1<N&&(grid[x][y+1]=='G'||grid[x][y+1]=='M')&&beeT[x][y]+1<beeT[x][y+1]){
            beeT[x][y+1]=beeT[x][y]+1;
            q.push({-beeT[x][y+1], {x,y+1}});
        }
    }
    int l=0,r=1e9;
    while(l<r){
        int mid=(l+r+1)/2;
        if(f(mid)){
            l=mid;
        }else{
            r=mid-1;
        }
    }
    cout << l << "\n";
    return 0;
}

• Subtask 1: 84 / 100